Endocardial Mapping Research Articles

B-PO04-079 HEAD-TO-HEAD COMPARISON OF ATRIAL CMR AND VOLTAGE MAPPING FOR PREDICTION CLINICAL OUTCOMES AFTER ATRIAL FIBRILLATION ABLATION

Atrial magnetic resonance imaging and endocardial voltage mapping are clinical tools for assessing atrial fibrosis. Both techniques have been reported to predict arrhythmia recurrence after catheter ablation of atrial fibrillation. However, it is not known how the predictive value of these techniques compare. To compare the predictive value of atrial MRI and atrial voltage mapping for predicting arrhythmia recurrence after catheter ablation of atrial fibrillation. Consecutive patients undergoing first-time atrial fibrillation ablation with prior atrial magnetic resonance imaging and high-density voltage mapping were included. Atrial magnetic resonance imaging and voltage maps were quantified using open source software (Cemrgapp, (www.cemrg.com) and OpenEP (www.openep.io), respectively). Clinical follow-up occurred over a median of 574 days using ECG and Holter monitoring. Paired magnetic resonance imaging and voltage mapping was performed in 122 patients. Linear regression demonstrated increasing low voltage area (<0.5mV) was associated with age, CHADS2VASc score and left atrial volume. However, cox proportional hazards assessment showed that atrial LGE (>3.3SD above the blood pool mean) was a significant predictor of arrhythmia recurrence (HR 1.04, i.e. risk of recurrence increased by 4% for each 1% increase in fibrosis, p = 0.01), where-as low voltage area was not (<0.5mV). Atrial LGE, but not low voltage area was significantly associated with recurrence of atrial fibrillation after ablation. However, low voltage area was closely related to common clinical comorbidities associated with atrial fibrillation.

B-011-20 EVALUATION OF THE 3-DIMENSIONAL SUBSTRATE OF VENTRICULAR TACHYCARDIA IN A LANGENDORFF PERFUSED HUMAN HEART

The underlying mechanisms of ventricular tachycardia (VT) are not well understood. Most models for VT propagation are based on animal studies or single surface recordings which have limited utility. Human based investigations of VT are often limited by hemodynamic collapse and lack viable ways to assess the myocardial electrical propagation. The authors seek to provide a novel method for the experimental evaluation of VT in human hearts with correlation to high resolution MRI fibrosis imaging. Human donor hearts were obtained from discarded transplant specimens. Following explant, the hearts were cannulated to the Langendorff apparatus and ventricular tachycardia was induced using a programmed ventricular stimulation protocol. Custom built 3D printed epicardial and endocardial mapping probes were deployed to map whole ventricular contraction. The hearts were imaged using high-resolution late gadolinium enhancement 4T MRI for fibrosis quantitation. A total of 8 human hearts underwent complete mapping procedures with 3 spontaneously beating VT hearts and 5 control hearts. High resolution mapping demonstrated VT originated from epicardial regions in all 3 hearts. Site of origin of VT was identified in all 3 human hearts and correlated to MRI fibrosis mapping. This study highlights new methods for the interrogation of ventricular tachycardia substrates using a novel human Langendorff heart model. The integration of mapping and imaging techniques in this study provides new insights into the mechanisms underlying VT. These efforts may help clinicians to provide more targeted ablation procedures.

B-PO01-066 FALLACIES OF AND NOVEL FINDINGS OF MAPPING INTRAMURAL ARRHYTHMOGENIC SOURCES USING ELECTROGRAM MORPHOLOGY

A unipolar ‘QS’ pattern is typically recorded adjacent to ventricular arrhythmogenic focal origin and indicative of a successful catheter ablation site. Alternatively, a unipolar ‘R’ wave infers a mapping site remote from the focal origin. We investigated unipolar electrogram (EGM) patterns generated by modifying the depth of an intramural focal source. Two models were created: an experimental and simulation model. Explanted healthy swine hearts were used in a Langendorff perfused heart model. An idealized human myocardial slab (up to 12mm thickness) was used in a simulation model with a 56-pole electrode grid represented on both endocardial and epicardial surfaces to generate unipolar EGMs. In the centre of the electrode grid, the intramural stimulation source depth varied between 1-10mm with increments of 1mm. A stimulus pacing depth of 1mm demonstrated unipolar ‘QS’ waves occupying 48% of the electrode array surface area, equating to an area of 64mm2. Distinct differences in unipolar EGM patterns and complexity were seen between epicardial and endocardial surface mapping (Figure). Endocardial maps showed at a depth of 1mm, a ‘R’ wave as the predominant unipolar pattern (54% of sites) whereas with an increasing depth of 5mm, ‘Q’ and ‘QS’ occupied >90% of sites and even up to 10mm, a ‘Q’ wave was the predominant pattern, occupying >70% of sites. On epicardial maps, a unipolar ‘QS’ pattern was rarely seen at superficial focal intramural sites (<5% of sites with a 1-2mm focal depth) whereas a ‘R’ wave was more commonly observed in 50% of sites. Furthermore, a monophasic ‘R’ wave was absent from all intramural sites >5mm, replaced largely by multi-component unipolar EGMs with increased complexity (QrS and qSS patterns). A ‘QS’ unipolar pattern lacks sensitivity for superficial foci and can be even the predominant pattern generated when mapping deep intramural foci >5mm at accessible mapping surface. Furthermore, a ‘R’ wave can be observed adjacent to superficial foci. Additionally, qSS pattern is a better indicated of deeper intramural focus at mapping surface. These findings suggest a revision is needed to electrogram morphology guided ablation of intramural arrhythmogenic foci.

B-PO03-122 DELINEATION OF 3D REENTRANT CIRCUITS USING EPICARDIAL-ENDOCARDIAL ELECTROCARDIOGRAPHIC IMAGING

Studies of VT mechanisms are largely based on a 2D portrait of reentrant circuits on one surface of the heart. This oversimplifies the 3D circuit that involves the depth of the myocardium. Simultaneous epicardial and endocardial (epi-endo) mapping was shown to facilitate a 3D delineation of VT circuits, which is however difficult via invasive mapping. We study the feasibility of noninvasive epi-endo electrocardiographic imaging (ECGi) in delineating 3D VT circuits. 120-lead ECGs of VT in combination with subject-specific heart-torso geometry are used to compute unipolar electrograms (CEGM) on ventricular epicardium and endocardia. Activation isochrones are constructed, and the percentage of activation within VT cycle length is calculated on each surface. This classifies VT circuits into 2D (surface only), uniform transmural, nonuniform transmural, and mid-myocardial (focal on surfaces). Critical circuit components, including exits and central isthmuses, are further localized. We analyzed 23 simulated and four in-vivo VT circuits on post-infarction porcine hearts. In simulated circuits, ECGi classified 21% as 2D and 78% as 3D: 82.6% of these were correctly classified (see Fig 1). In in-vivo circuits, ECGi classified 25% as 2D and 75% as 3D: in all cases, circuit exits and entrances were consistent with potential critical isthmus delineated from combined LGE-MRI and catheter mapping data. ECGi epi-endo mapping has the potential for fast delineation of 3D VT circuits, which may augment detailed catheter mapping for VT ablation.

Failure of radiofrequency catheter ablation and success of flecainide to suppress premature ventricular contractions in Andersen-Tawil syndrome: A case report

This case report presents a 33-year-old woman with premature ventricular contractions (PVCs). Her genetic testing was positive for KCNJ2 missense mutation at chr17:68171832;NM_000891.2. This mutation was compatible with Andersen-Tawil syndrome. We made an electrophysiological study to determine origin of PVCs however at endocardial mapping there was not any focus of PVC and at epicardial mapping we ablated low voltage areas in the inferior segments of both ventricles. She was discharged with flecainide and metoprolol therapy. After 3 months, her PVC burden was significantly decreased at Holter monitoring.

Global cardiac sympathetic denervation is associated with diffuse myocardial fibrosis in non-ischemic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: None. Background Occurrence of ventricular tachycardias (VT) has been related to changes in sympathetic innervation and myocardial tissue in ischemic cardiomyopathy. In non-ischemic cardiomyopathy (NICM) patients with VT, the relation between global cardiac sympathetic innervation and non-ischemic fibrosis is less clear. The current gold standard in electrophysiology to identify non-ischemic fibrosis relies on unipolar endocardial voltage mapping. Objective To establish the relationship between global cardiac sympathetic innervation and global fibrosis. Methods 29 patients (93% male, 58 ± 14 years, mean LVEF 38%±13) from the ‘Leiden Nonischemic Cardiomyopathy Study’ undergoing VT ablation between 2011-2018 were included. Endocardial voltage mapping was performed and the mean endocardial unipolar voltage (UV) was taken as a surrogate for global fibrosis. Global cardiac sympathetic innervation was analyzed by 123-I-MIBG imaging using heart-to-mediastinum ratio (HMR). A cut-off of 1.8 was used to delineate between normal (&amp;gt;1.8) and denervated (&amp;lt;1.8). HMR was correlated with mean UV. Results For patients with global cardiac sympathetic denervation a linear relationship was present between HMR and mean UV (R = 0.5278, P = 0.0431. There was no significant linear relationship for patients with normal cardiac sympathetic innervation between HMR and mean UV (R=-0.1696, P = 0.5795). Conclusion Global cardiac sympathetic denervation is related to myocardial fibrosis in patients with NICM and VT. The data support an interplay between denervation and fibrosis which may contribute to arrhythmogeneity, as observed in ICM. Abstract Figure.

Volume-weighted unipolar endocardial voltage: An excellent, novel parameter for predicting cardiac mortality in patients with dilated cardiomyopathy and ventricular arrhythmias

Abstract Funding Acknowledgements Type of funding sources: None. Background Patients with dilated cardiomyopathy (DCM) and ventricular tachyarrhythmias (VT) are at risk for heart failure (HF) death. Global left ventricular endocardial voltage may reflect the amount of excitable viable myocardium and identify patients at risk for rapid progression to end-stage HF. Aim To determine if volume-weighted endocardial voltage, as a surrogate for the total excitable viable myocardium, predicts mortality in patients with DCM and VT. Methods Consecutive patients with DCM, who underwent high-density endocardial voltage mapping for VT or PVC ablation (2012-2018), were included. Mapping data were transferred from CARTO to ParaView after excluding valve areas. The volume-weighted UV and BV (vwUV, vwBW) were calculated by mathematically integrating the UV and BV over the whole LV (thereby correcting for mapping density heterogeneity) divided by the endocardial LV surface area and corrected for LV wall thickness determined by echocardiography. The prognostic values of vwUV and vwBV for cardiac function and cardiac death were evaluated. Results One hundred three patients (VT, n = 83 and PVC, n = 20; age, 57 ± 14yrs; LVEF, 39 ± 13%; [likely] pathogenic genetic variants 33 [32%]; amiodarone use 36 [35%]) were included. VwUV and vwBV were 9.94 ± 3.42 and 4.70 ± 1.46. During a median follow-up of 24 months, cardiac mortality was 18% (end-stage HF 16/19, the median time to death 5.7 months). Patients who died had a significantly lower vwUV and vwBV (vwUV 5.62 ± 0.93 vs. 10.91 ± 3.10, P &amp;lt; 0.001; vwBV 2.99 ± 0.70 vs. 5.04 ± 1.28, P &amp;lt; 0.001). The optimal cutoff of vwUV for predicting HF-related death was 6.64 (AUC, 0.98; Sensitivity, 94%; Specificity, 95%), superior to LVEF or vwBV (AUC, 0.77, 0.92, respectively, Figure A). In multivariable analysis, vwUV remained the only significant predictor for cardiac death (for one decrease, HR 2.66, CI 1.41-5.00, P = 0.002), independently of LVEF, NT-proBNP, vwBV, genetic variants, and amiodarone use. In a subanalysis, the correlations between vwUV and changes of LVEF over time after voltage mapping were analyzed in patients with mid-range (HFmrEF, EF40-49%, n = 27) and reduced (HFrEF, EF &amp;lt; 40%, n = 53) LVEF, respectively. In patients with HFmrEF, a significant LVEF deterioration (defined as an EF decrease &amp;gt;5% and transition to HFrEF) occurred in 22% and was strongly related with a low vwUV (6.65 ± 1.15 vs. 10.08 ± 2.92, P = 0.02, Figure B left). Furthermore, in patients with HFrEF, a significant LVEF improvement (defined as an EF increase &amp;gt;5% and transition to HFmrEF) was noted in 32% and was correlated with a high vwUV (11.68 ± 2.70 vs. 8.62 ± 2.69, P = 0.002, Figure B right). Conclusion VwUV is a newly proposed surrogate for the amount of LV viable myocardium, available from routine endocardial mapping and an excellent parameter to identify patients with DCM at high risk for rapid progression to HF-related death. Abstract Figure. vwUV and outcomes

Cardiac reparative therapy with adipose graft transposition procedure reduces slow conduction areas in a chronic myocardial infarction swine model

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Insituto de Salud Carlos III BACKGROUND Cardiac regenerative therapy is a promising treatment for patients with ischemic heart disease, but there are some concerns on the potential increased risk of arrhythmic events following specific cell therapies. Adipose graft transposition procedure (AGTP) is a cardiac reparative therapy consisting in transposing a vascularized adipose flap from the autologous pericardium and placing it over the epicardial scar area and has demonstrated to reduce infarct size and improve the left ventricular ejection fraction in preclinical and human studies. Specific electrophysiological properties of the scar, (i.e. slow conduction velocity (CV)) have been identified as key features of ventricular tachycardia (VT) isthmuses. PURPOSE To assess the effect of the AGTP on VT inducibility and the electrophysiological properties of the post-MI scar with ultra-high density (UHD) mapping. METHODS A left circumflex artery (first marginal branch) MI was induced in 10 Landrace X Large White pigs by delivering 1-3 coils. Two weeks post-MI, all subjects underwent baseline left ventricular endocardial UHD mapping during right ventricular pacing with 64-electrode basket mapping catheter, as well as electrophysiological study (EPS) to test for VT inducibility. Following the mapping, subjects were allocated 1:1 to AGTP or sham group. UHD mapping and EPS were repeated 30 days post-treatment (6 weeks after MI). Voltage and activation maps were analyzed off-line with self-customized Paraview-based software. Voltage cut-offs of 1.5 and 0.5mV (bipolar) defined normal tissue, border zone (BZ) and dense scar, respectively, and 6.7mV for unipolar. Conduction velocity (CV) was determined for every pair of contiguous points and areas of similar CV were quantified for every 0.2m/s steps (for up to 4 m/s). RESULTS There were no differences between groups with regard of dense scar, BZ an low unipolar voltage areas. The AGTP group had a significant reduction of the size of slow CV (&amp;lt;0.2 m/s) areas, compared to the sham group in whom it increased (-4.1 ± 1.7 vs. +2.4 ± 1.6 mm2, p = 0.028)(Figure). There were no differences in the size of other ranges of CV. EPS did not induce VT in any subject at baseline, and only in 1 of the sham group at the follow-up EPS. CONCLUSIONS Cardiac reparative therapy with AGTP of post-MI scar reduced the size of slow conduction areas and could provide a protective effect against arrhythmic events in ischemic heart disease. Abstract Figure.

In-vivo endocardial and epicardial quantitative comparison of multi-wave based non-invasive inverse electrocardiography

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by the Dutch Heart Foundation Introduction Non-invasive mapping of ventricular activation using inverse electrocardiography (iECG) in patients with cardiomyopathy during sinus rhythm, may improve risk stratification for sudden cardiac death. However, iECG is complicated by multiple simultaneous endocardial activation waves (multi-wave) mediated by the His-Purkinje system, especially when the QRS complex is narrow. The activation estimation should be based on a realistic physiological model of the His-Purkinje system combining multiple waves initiated at His-Purkinje associated endocardial locations. Equivalent double layer based iECG provides an estimation of both the endocardial and epicardial surface. To improve accuracy, equivalent double layer based iECG was supplemented with electro-anatomical structures associated with the His-Purkinje system to test initial ventricular activation (Figure, Panel C). Multi-wave iECG local activation timing (LAT) maps and invasive LAT maps during sinus rhythm were quantitatively compared. Purpose Quantitative comparison of multi-wave iECG in His-Purkinje mediated cardiac activation using invasive activation maps in patients. Methods Thirteen patients referred for invasive electro-anatomical mapping (EAM) of the endocardial and epicardial surface were included. Prior to EAM, each subject underwent 64 electrode body surface potential mapping, cardiac computed tomography (CT) imaging, and 3D imaging of electrode positions. Anatomical models of the ventricles, lungs and thorax were created using CT images and supplemented with electrode positions (Figure, Panel A-B). Electro-anatomical structures associated with the His-Purkinje system were incorporated in ventricular anatomical models (Figure, Panel C) and multiple simultaneous activation waves were simulated. Invasive endocardial and epicardial LAT maps were quantitatively compared to iECG LAT maps. Invasive EAM LAT maps were quantitatively compared to estimated iECG LAT maps (Figure, Panel D) using inter-map correlation coefficients (CC, Pearson’s) and absolute differences (AD). Results Mean inter-map CC and AD were 0.54 ± 0.19 and 18 ± 7 ms respectively for the epicardial surface (n = 13). Similar to the RV endocardial surface (n = 10, CC = 0.50 ± 0.29, AD = 20 ± 8 ms) and the LV endocardial surface (n = 4, CC = 0.44 ± 0.26, AD = 25 ± 7 ms). Conclusion(s): Quantitative comparison of the multi-wave iECG method showed overall moderate performance. This novel iECG method provides a physiologically more realistic and more robust estimation of sinus rhythm and may serve as a tool for detection of electro-anatomical substrates and risk stratification. Compared to other available non-invasive ECG methods, multi-wave iECG captures His-Purkinje mediated ventricular activation better. This method might also be useful for the accurate detection and localization of structural conduction disorders. Abstract Figure. Multi-Wave inverse electrocardiography

Epicardial ablation of recurrent left atrial macroreentrant tachycardia from Bachmann's bundle region after endocardial ablation

Bachmann's bundle is a common site of possible epicardial connection in addition to coronary sinus, Marshall ligament and septopulmonary bundle. Hereby, we presented the image of epicardial ablation for recurrent perimitral macroreentry after endocardial ablation. Endocardial mapping revealed discontinuous activation pattern. Epicardial mapping demonstrated highly fragmented signals at the opposite site of presumed endocardial isthmus. Epicardial mapping and ablation may improve procedural success in selected patients with accurate definition of reentrant circuit despite effective endocardial lesion formation. This article is protected by copyright. All rights reserved.

The role of high-density mapping in atrial fibrillation ablation

Aims. To determine the role of the prevalence of low-voltage areas in the occurrence of arrhythmia recurrence after interventional treatment of atrial fibrillation (AF).Methods. The study included 38 patients with paroxysmal (52.6%) and persistent (47.4%) forms of AF who underwent interventional treatment of AF using high-density electroanatomical mapping (at least 10,000 EGM points). Analysis of electroanatomical maps was performed after the completion of the ablation procedure. The area of the low-voltage zones was measured manually. Then, the areas of all regions of low-voltage activity were summed up; the resulting value was expressed as a percentage of the total surface area of the left atrium (LA).Results. The observation period was 12.8±3.2 months. Based on the results of endocardial mapping, all patients were divided into 2 groups according to the prevalence of low-voltage areas in the LA. The first group included patients with an area of low-voltage zones less than 5% of the total surface of the left atrium, and the second with an area of low-voltage areas of more than 5% of the total surface of the left atrium. The patients of the first group had a lower LA volume compared to patients from the second group, with mean values of 119.87±16.35 ml and 154.57±33.23 ml, respectively (p=0.007). In the first group, AF recurrence was recorded in one patient after catheter treatment, in the second group in 5 patients.Conclusion. Common areas of low-voltage activity in the left atrium, detected by high-density mapping before the procedure for catheter treatment of AF, are a predictor of arrhythmia recurrence after interventional treatment.

Echocardiographic diagnosis of atrial cardiomyopathy allows outcome prediction following pulmonary vein isolation

BackgroundRelevant atrial cardiomyopathy (ACM), defined as a left atrial (LA) low-voltage area ≥ 2 cm2 at 0.5 mV threshold on endocardial contact mapping, is associated with new-onset atrial fibrillation (AF), higher arrhythmia recurrence rates after pulmonary vein isolation (PVI), and an increased risk of stroke. The current study aimed to assess two non-invasive echocardiographic parameters, LA emptying fraction (EF) and LA longitudinal strain (LAS, during reservoir (LASr), conduit (LAScd) and contraction phase (LASct)) for the diagnosis of ACM and prediction of arrhythmia outcome after PVI.MethodsWe prospectively enrolled 60 consecutive, ablation-naive patients (age 66 ± 9 years, 80% males) with persistent AF. In 30 patients (derivation cohort), LA-EF and LAS cut-off values for the presence of relevant ACM (high-density endocardial contact mapping in sinus rhythm prior to PVI at 3000 ± 1249 sites) were established in sinus rhythm and tested in a validation cohort (n = 30). Arrhythmia recurrence within 12 months was documented using 72-h Holter electrocardiograms.ResultsAn LA-EF of < 34% predicted ACM with an area under the curve (AUC) of 0.846 (sensitivity 69.2%, specificity 76.5%) similar to a LASr < 23.5% (AUC 0.878, sensitivity 92.3%, specificity 82.4%). In the validation cohort, these cut-offs established the correct diagnosis of ACM in 76% of patients (positive predictive values 87%/93% and negative predictive values 73%/75%, respectively). Arrhythmia recurrence in the entire cohort was significantly more frequent in patients with LA-EF < 34% and LASr < 23.5% (56% vs. 29% and 55% vs. 26%, both p < 0.05).ConclusionThe echocardiographic parameters LA-EF and LAS allow accurate, non-invasive diagnosis of ACM and prediction of arrhythmia recurrence after PVI.Graphic abstract

Intraprocedural arrhythmia termination as an end point for hybrid ablation in patients with long-standing persistent atrial fibrillation: a 2-year follow-up study.

Hybrid catheter and surgical ablation has emerged as an effective therapy for patients with persistent atrial fibrillation (AF). The aims of this study were to evaluate the relationship between intraprocedural arrhythmia termination and the long-term outcomes of hybrid ablation in patients with long-standing persistent AF. From May 2015 through April 2019, 50 patients with persistent AF with a mean duration of 73.3 ± 62.1 (median 54) months underwent single-step hybrid ablation. Pulmonary vein isolation, left atrial posterior wall isolation and left atrial appendage excision or closure were performed through a left-sided thoracoscopic approach. Subsequently, all patients underwent high-density endocardial mapping and electrogram-based ablation with the end point of AF termination. We achieved intraprocedural AF termination in 84% (42/50) patients; this end point was reached in 16 patients during surgical ablation and in 26 patients during catheter ablation. Seven patients underwent repeat catheter ablation. After a mean follow-up period of 29 ± 13 months, the freedom from atrial tachyarrhythmia of a single procedure without the use of antiarrhythmic drugs was 70% (35/50). In the Cox regression model, intraprocedural termination of AF (hazard ratio 0.205, 95% confidence interval 0.058-0.730; P = 0.014) was the sole predictor of success. The 2-year outcomes of a one-stop hybrid ablation with an end point of AF termination are promising in patients with long-standing persistent AF.

Immediate electrophysiological characteristics following modified thoracoscopic ablation via unilateral approach for non-valvular atrial fibrillation

Thoracoscopic ablation has emerged as an effective therapy for patients with long-standing persistent Atrial fibrillation (LsPAF). We aimed to investigate the immediate electrophysiological characteristics following modified ablation with 3 circular and 3 linear lesions in the thoracoscopic procedure via a unilateral approach. Between May 2015 and October 2018, 40 patients underwent the one-stage hybrid procedure for LsPAF. Isolation of the pulmonary veins (PV) and left atrium posterior wall (LAPW), excision of the left atrial appendage (LAA), and high-density endocardial mapping and individualized percutaneous catheter ablation for AF termination were performed. The modified thoracoscopic procedure may enable successful PV and LAPW isolation and LAA removal. Endocardial electrophysiological examination showed 6 out of 40 (15%) patients with a right PV gap, 3 (7.5%) patients with incomplete roof lesions, and 8 (20%) patients with incomplete Dallas lesions. A total of 44 driving areas were mapped and ablated. Thirty-five patients achieved procedural AF termination. After a mean follow-up period of 26months, the success rate of a single procedure was 85%. Cox regression analysis demonstrated that the failure of procedural AF termination may be a risk factor in atrial tachyarrhythmia recurrence. Endocardial electrophysiological examination is a necessary partner to thoracoscopic ablation. Our modified thoracoscopic ablation and driving areas-based ablation contribute to high rates of procedural AF termination, which may lead to reduced recurrence rate. The hybrid procedure may be an effective strategy for the management of LsPAF.

Efficient identification of scars using heterogeneous model hierarchies.

Detection and quantification of myocardial scars are helpful for diagnosis of heart diseases and for personalized simulation models. Scar tissue is generally characterized by a different conduction of excitation. We aim at estimating conductivity-related parameters from endocardial mapping data. Solving this inverse problem requires computationally expensive monodomain simulations on fine discretizations. We aim at accelerating the estimation by combining electrophysiology models of different complexity. Distributed parameter estimation is performed by minimizing the misfit between simulated and measured electrical activity on the endocardial surface, subject to the monodomain model and regularization. We formulate this optimization problem, including the modelling of scar tissue and different regularizations, and design an efficient solver. We consider grid hierarchies and monodomain-eikonal model hierarchies in a recursive multilevel trust-region method. With numerical examples, efficiency and estimation quality, depending on the data, are investigated. The multilevel solver is significantly faster than a comparable single level solver. Endocardial mapping data of realistic density appears to be sufficient to provide quantitatively reasonable estimates of location, size, and shape of scars close to the endocardial surface. In several situations, scar reconstruction based on eikonal and monodomain models differ significantly, suggesting the use of the more involved monodomain model for this purpose. Eikonal models can accelerate the computations considerably, enabling the use of complex electrophysiology models for estimating myocardial scars from endocardial mapping data.

Nonatrial Fibrillation Patients With Complete P Wave Disappearance: An Overlooked Population With High Stroke Risk.

Complete P wave disappearance (CPWD) in patients without atrial fibrillation is an uncommon clinical phenomenon. We aimed to study the relationship between CPWD and thromboembolism. Between July 2007 and December 2018, consecutive patients with CPWD on surface ECG and 24-hour Holter recording were recruited into the study from 4 centers in China. All recruited patients underwent transesophageal echocardiography or cardiac computed tomography to screen for atrial thrombus. Atrial electrical activity and scar were assessed by electrophysiological study (EPS) and 3-dimensional electroanatomic mapping. Cardiac structure and function were assessed by multimodality cardiac imaging. Twenty-three consecutive patients (8 male; mean age 48.5±14.7 years) with CPWD were included. Only 3 patients demonstrated complete atrial electrical silence with atrial noncapture. Thirteen patients who had invasive atrial endocardial mapping demonstrated extensive scar. Pulse-wave mitral inflow Doppler demonstrated absent and dampened A waves in 18 and 5 patients, respectively. Pulse-wave tricuspid inflow Doppler showed absent and dampened A waves in 19 and 4 patients, respectively. Upon recruitment, 8 patients had previous stroke and 3 patients had atrial thrombus. Warfarin was prescribed to all patients. During median follow-up of 42.0 months, 2 patients developed massive ischemic stroke due to warfarin discontinuation. Our study suggested that CPWD reflects extensive atrial electrical silence and significantly impaired atrial mechanical function. It was strongly associated with thromboembolism and the clinical triad of CPWD-atrial paralysis-stroke was proposed. Anticoagulation should be recommended in such patients.

Spatial and transmural properties of the reentrant ventricular tachycardia circuit in arrhythmogenic right ventricular cardiomyopathy: Simultaneous epicardial and endocardial recordings

While advances in the characterization of the structural substrate in arrhythmogenic right ventricular cardiomyopathy (ARVC) have been made, the ventricular tachycardia (VT) circuit remains incompletely described. The purpose of this study was to delineate the reentrant VT circuit with simultaneous epicardial and endocardial mapping (SEEM) in ARVC. Twenty-three consecutive patients with ARVC and VT underwent SEEM at 4 centers between 2014 and 2020. Retrospective analysis was performed on combined isochronal activation maps. Of the 30 VT circuits, 24 were delineated with SEEM (956 [341-1843] endocardial points and 1763 [882-3054] epicardial points). The apex and outflow tract rarely harbored VT circuits, with 50% distributed in the inferior wall and 43% in the free wall. The entire tachycardia cycle length was recorded from the epicardium in 71% of circuits. In all circuits, a large proportion of the tachycardia cycle length was recorded from the epicardium relative to the endocardium. Localized epicardial reentry was observed in 35% of patients (14 mm × 15 mm), which was associated withsmaller endocardial low voltage area (39 cm2 vs 104 cm2; P= .002) and preserved right ventricular ejection fraction (35% vs 25%; P = .046) compared with those with larger circuit dimensions. Seventy percent of termination sites were achieved from the epicardium. High-resolution recordings from both myocardial surfaces confirm a consistent predominance of epicardial participation during reentry in ARVC. Only the perivalvular inflow region of the "triangle of dysplasia" had a strong propensity to harbor VT circuits, with the greatest proportion located in the inferior wall. Localized epicardial reentry may be a manifestation of earlier stage disease with a relative paucity of endocardial substrate.

Electrocardiographic and Electrophysiological Characteristics of Idiopathic Ventricular Arrhythmias Ablated Through Percutaneous Trans-Pericardial Approach

BackgroundIdiopathic epicardial ventricular arrhythmias (VAs) are clustered in the areas of the summit and crux.ObjectiveTo report a group of idiopathic epicardial VAs remote from the summit and crux areas.MethodsIn total, 9 patients (6 males, mean age 32{plus minus}13 years) were enrolled. The locations were identified by epicardial mapping and ablation. The electrocardiographic and electrophysiological characteristics were compared to those of 9 patients who had VAs ablated at the opposite endocardial site.ResultsVAs were identified at the epicardium, with 4 patients had VAs located at the inferior wall, one at the anterior wall, one at the apex and 3 patients had VAs at the lateral wall. A QS type at the location-related leads was the only identified surface electrocardiogram indication suggesting epicardial origin (compared to that of the controls, 100% vs 0%, p<0.001). Endocardial and epicardial mapping revealed pre-maturities of -11{plus minus}4 ms and -25{plus minus}8 ms, respectively (VS. -28{plus minus}8 ms revealed by endocardial mapping in control patients, p<0.001 and p=0.389, respectively). All of the study cases demonstrated an rS pattern in the endocardial unipolar electrogram. Acute and long-term successful ablation (a median of 11 months of follow-up) was achieved in all patients without complications.ConclusionA distinct group of idiopathic VAs remote from the summit and crux areas warranting ablation by a subxiphoid approach were identified. Morphological ECG features of a QS type among the location-related grouped leads combined with the mapping findings helped in the identification of the epicardial site of origin.

Relations between voltage mapping and diagnosis and genetics in patients with arrhythmogenic right ventricular cardiomyopathy

Relations between voltage mapping and diagnosis or genetic background in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) have not been investigated so far. We investigate if diagnosis or genetic background were linked to voltage mapping in ARVC. Seventy patients with proved or suspected ARVC undergoing 3D endocardial voltage mapping and genetic testing have been retrospectively included. Localisation and extension of bipolar low voltage areas were correlated to ARVC diagnosis and presence of a culprit mutation. Forty-four over seventy fulfilled ARVC Task Force criteria and 25/70 had culprit mutations. Endocardial (38/44 vs. 16/26, P = 0.02) and especially infero-lateral scars (31/44 vs. 9/26, P = 0.003) were more often present in patients fulfilling Task force criteria vs. suspected ARVC, with larger scars (area 23 ± 27 vs. 8 ± 11 cm2, P = 0.04, perimeter 17 ± 10 vs. 11 ± 7 cm, P = 0.03) (sensitivity 86%). Mutated patients had more infero-lateral (19/25 vs. 21/45, P = 0.01), multiple (12/20 vs. 11/34, P = 0.04) and larger scars (perimeter 21 ± 10 vs. 12 ± 7 cm, P = 0.01) vs. non-mutated patients. In patients with ARVC diagnosed according to the Task Force criteria, there was a trend toward more infero-lateral (P = 0.09) and larger scars (P = 0.08) in mutated cases. PKP2-mutated cases tended to have less ourflow tract (P = 0.08) and less multiple scars (P = 0.09) vs. other mutations (Fig. 1). 3D endocardial mapping could have an important role for ARVC diagnosis and may be able to detect minor forms with otherwise insufficient criteria for diagnosis. More frequent and larger infero-lateral scars are present in mutated patients with borderline differences according to the mutated genes.

A Case Report of Radiofrequency Ablation of Typical Atrial Flutter Combined with Atrial Tachycardia

A 63-year-old female patient with a history of pulmonary heart disease underwent radiofrequency ablation because of a persistent atrial flutter. Endocardial mapping with the carto3 system confirmed atrial flutter counterclockwise reentry around the tricuspid annulus. Routine ablation of the cavo-tricuspid isthmus line to bi-directional block was performed. However, tachycardia with the same cycle length was induced again. After remapping, the tachycardia was confirmed to be focal atrial tachycardia located in the crista terminalis. After ablation, the tachycardia was terminated and could not be induced again.